Just about every medium that tells a story seems to eventually develop universes - collections of lore and history originally attached to particular stories, but that stay relevant long after those initial tales are completed. The allure of the universe is stronger than any individual story told within it, so people come back time and time again, demanding new stories told within its confines.

Television gives us some of the most numerous and obvious examples. Star Trek, for instance, is a terrific analogue for what Mass Effect could be. Its universe has sustained multiple television series, books, movies, games, and more. While the original show that started it all still remains popular, clearly there is more draw here than just Kirk and his crew.

Another obvious example, this time from the world of film, is Star Wars. There should be no need to explain the importance of this one. It is one of the most influential story universes of all time. It strongly centers around the original movies which made it famous, but has produced countless examples of other forms of entertainment only related by the universe they share.